Process for preparing a copolymer of ethylene and a conjugated diene

ABSTRACT

AN ALTERNATING COPOLYMER AND/OR AN ETHYLENE RICH RANDOM COPOLYMER OF ETHYLENE AND A CONJUGATED DIENE IS FORMED BY REACTION IN THE PRESENCE OF A CATALYST COMPRISING AN ORGANOALUMINUM COMPOUND AND A TITANIUM TETRAHALIDE. THE CHARACTERISTIC FEATURE OF THE ALTERNATING COPOLYMER IS AT THE CONFIGURATION OF THE CONJUGATED DIENE UNITS IN THE COPOLYMER IS NOT STEROSPECIFIC AND THE COPOLYMER SHOWNS RUBBER-LIKE ELASTICITY. THE RANDOM COPOLYMER HAS NO DIENE-DIENE LINKAGE.

April 9, 1974 KIYOSHIGE HAYASH ETAL 3,803,106 PROCESS FOR PREPARING ACOPOLYMER OF ETHYLENE AND A CONJUGATED DIENE Filed March 15, 1971 9Sheets-Sheet 1 Ap 9. 1974 KIYOSHIGE HAYASHI ET 3,303,106

PROCESS FOR PREPARING A COPQLYMER OF ETHYLENE AND A CONJUGATED DIENEFiled March 15, 1971 9 Sheets-Sheet 2 F ig. 2

p 1974 KIYOSHIGE HAYASHI TA 3,803,106 PROCESS FOR PREPARING A COPOLYMEROF ETHYLENE AND A CONJUGATED DIENE Filed March 15, 1971 9 Sheets-Sheet 5A ril 9. 1974 KIYOSHIGE HAYASHI ETAL Filed March 15, 1971 A CGNJUGATEDDIENE 9 Sheets-Sheet 4 A nl 9. 197 KIYOSHIGE HAYASHI L 03,

} PROCESS FOR PREPARING A COPOLYMER OF ETHYLENE AND A CONJUGATED DIENEFiled M67011 1.5 1971 9 Sheets-Sheet 5 Ap 9, 1974 KIYOSHIGE HAYASHI A3,803,106 PROCESS FOR PREPARING A CQPOLYMER 0F ETHYLENE AND A CONJUGATEDDIENE Filed March l5 1971 9 Sheets-Sheet 6 O Q I I I I I I I W I I I I II I 3500 2500 I500 I000 5CD Apnl 9, 1974 KlYOSHiGE HAYASH] ErAL3,803,106 PROCESS FOR PREPARING A COPOLYMER OF ETHYLENE AND A CONJUGATEDDIENE Filed March l5 1971 9 Sheets-Sheet 7 Fig. 8

A ril 9, 1974 KIYOSHIGE HAYASHI Filed March l5 1971 A CONJUGATED DIENE 9Sheets-Sheet 8 Ap 9, 1974 KIYOSHIGE HAYASHI E 3,303,105 PROCESS FORPREPARING A COPOLYMER 0F ETHYLENE AND A CONJUGA'IED DIENE Filed larch l51971 9 Sheets-Sheet 9 United States Patent 3,803,106 PROCESS FORPREPARING A COPOLYMER OF ETHYLENE AND A CONJUGATED DIENE KiyoshigeHayashi, Tokyo, and Akihiro Kawasaki and Isao Maruyama, Ichihara, Japan,assignors to Maruzen Petrochemical Co., Ltd., Tokyo, Japan Filed Mar.15, 1971, Ser. No. 124,281 Claims priority, application Japan, Mar. 19,1970, 45/22,676; Apr. 13, 1970, 45/30,761 Int. Cl. C08d 1/14, 3/06, 3/10US. Cl. 26085.3 R 19 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THEINVENTION (1) Field of the invention The present invention relates to anovel alternating copolymer of conjugated diene and ethylene whosemicrostructure of conjugated diene is lacking in stereospecificity. Thealternating copolymer of conjugated diene and ethylene shows rubber-likeelasticity.

The present invention further relates to a process for preparing acopolymer of conjugated diene and ethylene, and more particularly,relates to a process for preparing an alternating copolymer ofconjugated diene and ethylene whose microstructure of conjugated dieneunits is lacking in stereospecificity and an ethylene rich randomcopolymer of conjugated diene and ethylene at the same time. The ratioof the alternating copolymer to the random copolymer in the reactionproduct can be varied widely by controlling the polymerizationconditions. At the ultimate conditions, the former or latter copolymeralone can be prepared.

(2) Description of the prior act British Pat. 776,326 (1957), US. Pat.2,968,650 (1961) and German Pat. 1,144,924 (1963) reported a process forpreparing a copolymer of ethylene and butadiene by using a catalystsystem of titanium (IV) chloride and phenyl magnesium bromide, a processfor preparing a copolymer of ethylene and butadiene by using a catalystsystem of titanium (IV) chloride and lithium aluminum hydride and aprocess for preparing a copolymer of ethylene and isoprene by using acatalyst system of titanium (IV) chloride and lithium aluminumtetrabutyl. These copolymers were shown to be polyethylene modified by10-20% butadiene or by a minor amount of isoprene units. British Pat.893,462 (1962) and US. Pat. 3,244,678 (1966) described the process forpreparing a copolymer of ethylene and isoprene by using a coordinationcatalyst system composed of triisobutylaluminum and vanadyl chloride.The ethylene unit content of the copolymer was in the range of 99% to90% by weight. The microstructure of isoprene unit of the copolymer was1,2 and 3,4-structures. The patents also described that the copolymermay be in the form of block copolymer, graft copolymer or randomcopolymer. On the other hand, Suminoe (Kobunshi Kagaku, 20, 467 (1963),Kobunshi Gakkai, Tokyo, Japan) reported a copolymerization reaction ofethylene and isoprene in the presence of triethylaluminum-titanium (IV)chloride Patented Apr. 9, 1974 catalyst system. The copolymerizationreaction was carried out by introducing a gaseous mixture of ethyleneand nitrogen at a predetermined rate into a n-hexane solution ofisoprene and catalyst system at the temperature of an ice-water systemand at atmospheric pressure. The copolymer was fractionated into 2fractions by benzene extraction, however both fractions were determinedto be block-type copolymers.

Belgian Pats. 625,657 (1963), and 625,658 (1963), Japanese patentpublications 14,813/1964, and 14,814/ 1964 and Italian Pat. 664,769(1964) described that linear vulcanizable copolymers of conjugateddiolefins and ethylene were produced by using a catalyst systemcontaining a hydrocarbon soluble vanadium compound, such as a halide,oxyhalide, alkoxide or acetyl-acetonate, e.g. vanadium (IV) chloride,vanadium (III) chloride or vanadium (IV) bromide and an organoaluminumcompound containing at least one organic group having strong stericalhindrance, e.g. 3-methyl-butyl, cycloalkyl or cyclopentylmethyl. Atleast one valency of vanadium and (or) aluminum of the catalyst systemwas also saturated by a halogen atom. The copolymers obtained weredetermined to be completely amorphous from X-ray examinations. Thepatents also described that the distribution of unsaturated units in thecopolymers is more homogeneous than that of the one prepared by anyprevious methods. Therefore, the copolymer is considered to be a randomcopolymer of a conjugated diolefin ethylene.

British Pat. 1,112,698 (1968) and Japanese patent publication11,303/1970 described processes for preparing an unsaturated,crsytalline copolymer comprising macromolecules made up of copolymerizedunits of ethylene and butadiene in whichthe butadiene units have anessentially trans-1,4 structure and containing from 0.1 to 5 mol percentbutadiene, which copolymers do not exhibit crystallinity typical ofbutadiene units of trans-1,4 type by using a catalyst consisting ofthe'reaction product of a complex having the formula TiCl 2PR wherein Ris an aryl, radical, with an aluminum dialkyl monochloride. Boilingn-heptane insoluble fraction of the copolymer showed, under X-ray, highcrystallinity of polyethylene type, while the infrared spectrum showedunsaturation of trans-type. The copolymer was determined to be a randomcopolymer of ethylene and butadiene having homogeneous distribution ofunsaturated units.

'French Pats. 1,302,656 (1962)and 1,334,941 reported the processes forpreparing copolymers of ethylene and butadiene having a low content ofbutadiene unit by using a catalyst system of triethylaluminum ordiethylaluminum monochloride, vanadium (IV) chloride and trichloroaceticacid. The copolymer is considered to be a linear polyethylene modifiedby small amounts of butadiene unsaturation.

Japanese patent publication 17,144/ 1969 also described a process forpreparing a random copolymer of ethylene and butadiene having a lowcontent of butadiene unit by using titanium (1V) chloride,diethylaluminum monochloride and a tertiary diphosphine compound.

At any rate, there are shown no descriptions with respect to anyalternating copolymer of conjugated diene and ethylene and the processfor preparing the alternating copolymer in the above references.

Natta (Makromol. Chem. 79, 161 (1964)) reported that a copolymer ofbutadiene and ethylene was prepared at 25 C. by using a catalyst systemof triisobutylaluminum, diisobutylaluminum monochloride, anisol andvanadium (IV) chloride mixed at 78 C. 1.20% of the crude copolymer was an-pentane soluble and diethyl ether insoluble fraction. The fraction wascrystalline and its X-ray diagram showed the presence of peaks at angles2a'=ZO.3 and 23. The mol percent of ethylene unit in the fraction was50.6% and its intrinsic viscosity was 0.25 (dl./g.). The melting pointof the fraction was 60- 65 C. The infrared spectrum of the copolymershowed crystallization sensitive bands at 1206, 1070 and 889 cmr On theother hand, although the microstructure of butadiene unit of thefraction was essentially trans-1,4, bands attributable to crystallinetrans-1,4 polybutadiene could not be detected at 1235, 1054 and 773 cmrFrom the above results, the fraction was determined to be an alternatingcopolymer.

French Pat. 1,361,801 (1964) reported a crystalline copolymer ofbutadiene and ethylene having two peaks at 20.5 and 23.2 in the X-raydiagram and showing three bands at 8.27, 9.25 and 11.20 microns in theIR spectrum and the method for preparing the copolymer by a catalystsystem of vanadium (IV) chloride, trialkylaluminum, dialkylaluminummonochloride and anisol.

Miyoshi (21st Annual Meeting of Japan Chemical Society, Tokoyo, 1968)also reported an alternating copolymerization of butadiene and ethylene.When the feeding rate of gaseous monomers was high, a catalyst system oftitanium (IV) chloride, triethylaluminum and diethylaluminummonochloride produced a mixture of polyethylene and polybutadiene, onthe other hand, when the feeding rate was low, the catalyst systemproduced a crystalline-alternating copolymer of butadiene and ethylene.The alternating copolymer was separated from the reaction product as abenzene soluble fraction. The molecular weight of the alternatingcopolymer was LOGO-3,000 and its melting point was at 60 C.

SUMMARY OF THE INVENTION In accordance with this invention, we havefound that by using the catalyst system composed of the first componentof an organoaluminum compound having the general formula of AlR whereinR represents a hydrocarbon radical selected from the group consisting ofa (l -C preferably C C and more preferably C C alkyl, cycloalkyl, aryland aralkyl radicals and the second component of titanium (IV) halidehaving the general formula of TiX; (wherein X represents halogen,hereinafter the same) or by using the catalyst system composed of thefirst component of an organoaluminum compound having the general formulaof AlRg wherein R is as defined above, the second component of titanium(IV) halide having the general formula of TiX (wherein X is the same asthat defined above) and the third component of a carbonyl groupcontaining compound, high molecular weight alternating copolymers ofconjugated diene and ethylene whose microstructure of conjugated dieneis lacking in stereoregularity and high molecular weight ethylene richrandom copolymers of conjugated diene and ethylene can be prepared atthe same time. The ratio of the alternating copolymer to the randomcopolymer in the reaction product can be varied widely by controllingthe polymerization conditions. For example, by decreasing the molarratio of conjugated diene to ethylene in the initial monomercomposition, the ratio of the alternating copolymer to the randomcopolymer in the reaction product decreases and vice versa. Also, theratio changes in accordance with the selection of the catalyst systememployed. To obtain a high ratio of alternating copolymer to randomcopolymer in the reaction product, it is also necessary to conduct thepolymerization reaction at mild conditions. At the ultimate conditions,the former or the latter copolymer alone can be prepared.

The alternating copolymer of conjugated diene and ethylene can beseparated from the ethylene rich random copolymer of the conjugateddiene and ethylene by usual solvent extraction methods. For example, thealternating copolymer is soluble in chloroform, n-heptane, toluene,diethyl ether, etc.; on the other hand, an ethylene rich 4 randomcopolymer of conjugated diene and ethylene is insoluble in the abovesolvents.

The alternating copolymers of conjugated diene and ethylene of thepresent invention are rubber-like in character and can be used aspolymeric plasticizers, in adhesives and can be vulcanized with sulphuror a sulphur compound to produce vulcanized elastomers. The ethylenerich random copolymers of conjugated diene and ethylene are also usefulbecause by vulcanization with sulphur based mixes they can betransformed into products having mechanical properties. By addingpredetermined amounts of rubber-like alternating copolymer of conjugateddiene and ethylene into an ethylene rich random copolymer of conjugateddiene and ethylene, the mechanical properties of the random copolymeralso can be modified.

The organoaluminum compounds which form the first component of thecatalyst system of this invention are defined by the formula AlR whereinR is a hydrocarbon radical selected from the group consisting of a (l -Cpreferably C -C and more preferably C -C alkyl, cycloalkyl, aryl andaralkyl radicals. Mixtures of these organoaluminum compounds may also beemployed. Examples of organoaluminum compounds falling within thedefinition include the following: trimethylaluminum, triethylaluminum,tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum,triisobutylaluminum, tripentyaluminum, trihexylaluminum, num,trioctylaluminum, triphenylaluminum, tri-p-tolylaluminum,tribenzylaluminum, ethyldiphenylaluminum, ethyl di-p-tolylaluminum,ethyldibenzylaluminum, diethylphenylaluminum, diethyl-p-tolylaluminum,diethylbenzylaluminum and the like. Mixtures of these compounds may alsobe employed. Of these, it is usually preferred to employtrialkylaluminum compounds.

The carbonyl group containing compounds which form the third componentof the catalyst system of this invention are carbon dioxide, aldehyde,ketoaldehyde, ketone, carboxylic acid, keto-carboxylic acid,oxy-carboxylic acid, carboxylic acid halide, keto-carboxylic acidhalide, oxycarboxylic acid halide, carboxylic acid anhydride,ketocarboxylic acid anhydride, oxy-carboxylic acid anhydride, salt ofcarboxylic acid, salt of keto-carboxylic acid, salt of oxy-carboxylicacid, ester of carboxylic acid, ester of keto-carboxylic acid, ester ofoxy-carboxylic acid, carbonyl halide, carbonate, carbonic ester,lactone, ketene, quinone, acyl peroxide, metal complex involvingcarbonyl group, acid amide, acid irnide, isocyanate, aminoacid, urein,ureide, salt of carbamic acid, ester of carbamic acid, ureide acid, etc.Mixtures of these compounds may also be employed.

The components of the catalyst system are normally employed in catalyticquantities. In the preferred embodiment, the molar ratio oforganoaluminum compound which forms the first component of the catalystsystem of the present invention to titanium (IV) halide which forms thesecond component of the catalyst system should be higher than 1.0 (Al/Ti1.0) and preferably the ratio should be higher than 1.5 (Al/Ti 1.5).

In the preferred embodiment, the molar ratio of carbonyl groupcontaining compound which forms the third component of the catalystsystem of this invention to titanium (IV) halide which forms the secondcomponent of the catalyst system of this invention should be in therange of 0.01 to 20 (0.01 C=O/Ti 20), the optimum ratios will be foundbetween 0.02 and 10 In the present invention, the activity of the threecomponents catalyst system of an organoaluminum compound having thegeneral formula of MR3, titanium (IV) halide and a carbonyl groupcontaining compound is higher than that of the two components catalystsystem of an organoaluminum compound having the general formula of AIR;and titanium (IV) halide.

tricyclohexylalumi- The conjugated dienes to be used in the presentinvention have from 4 to 12 carbon atoms, and typical examples arebutadiene, pentadiene-l,3, hexadiene1,3, isoprene, 2-ethyl butadiene,2-propyl butadiene, 2-isopropyl butadiene, 2,3-dimethyl butadiene,phenyl butadiene and the like. Among them, butadiene and isoprene arepreferable. A mixture thereof may also be employed.

The process for preparing the catalyst system of this invention has notbeen found to be critical. The organoaluminum compound which forms thefirst component of the catalyst system and titanuim (IV) halide whichforms the second component of the catalyst system or the organoaluminumcompound, titanium (IV) halide and the carbonyl group containingcompound which forms the third component of the catalyst system of thepresent invention can, be mixed per se or they may be dissolved in someorganic solvents. If a solvent is to be employed, the aromatic solventsuch as benzene, toluene, xylene and the like; the aliphatichydrocarbon, e.g. propane, butane, pentane, hexane, heptane, cyclohexaneand the like; the halogenated hydrocarbon solvent such as trihaloethane,methylene halide, tetrahaloethylene and the like, are usually preferred.In general, the temperature at which the components of the catalystsystem may be mixed covers a very wide range from 100 C. to +100 C.,preferably from 78 to +50 C.

Polymerization temperature may be from l C. to +100 C., preferably from78 C. to +50 C.

The practice of this copolymerization is usually carried out in thepresence of an organic solvent or diluent. However, this does not meanthat this invention cannot be practiced by employing bulkpolymerization, i.e. without the use of solvent. If it is desired to usea solvent, the aromatic solvent such as benzene, toluene, xylene and thelike; the aliphatic hydrocarbon, e.g. propane, butane, pentane, hexane,heptane, cyclohexane and the like; halogenated hydrocarbon solvent suchas trihaloethane, methylene halide, trihaloethylene and the like arepreferred.

At the completion of the copolymerization, the products may beprecipitated and deashed by using a methanol-hydrochloric acid mixture.The precipitated product may further be washed with methanol for severaltimes and dried under vacuum. As occasion demands, ethylene rich randomcopolymer of conjugated diene and ethylene is removed from theprecipitated product by usual solvent extraction methods. Thealternating copolymer of conjugated diene and ethylene of the presentinvention is soluble in chloroform, n-heptane, toluene, diethyl ether,etc.; on the other hand an ethylene rich random copolymer of conjugateddiene and ethylene is insoluble in the above solvents.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows the infrared spectrum ofa solid film of an alternating copolymer of butadiene and ethylene ofthe present invention on rock salt, intrinsic viscosity thereof wasfound to be 2.38 (dl./g.) in toluene at 30 C., and its melting point wasfound to be 23 C. by DSC measurement;

FIG. 2 shows the 60 mI-Iz. nuclear magnetic resonance spectrum of thecopolymer employed in FIG. 1 and the spectrum shown shifted upward isthe 100 mHz. nuclear magnetic resonance spectrum of the copolymer;

FIG. 3 shows the X-ray diffraction diagram of the copolymer employed inFIG. 1;

FIG. 4 shows the X-ray diffraction diagram of the copolymer employed inFIG. 1 which was stretched at 25 0.;

FIG. 5 shows the 60 mHz. nuclear resonance spectrum of an ethylene richrandom copolymer of butadiene and ethylene of the present invention;

FIG. 6 shows the infrared spectrum of a solid film of an alternatingcopolymer of butadiene and ethylene of the present invention on rocksalt, and the melting point of the copolymer was observed at 32 C. byDSC;

FIG. 7 shows the infrared spectrum of a solid film of 6 a highlycrystalline alternating copolymer of butadiene and ethylene on rock saltwhose microstructure of butadiene units in the copolymer is essentiallytrans-1,4 and the spectrum shown in a rectangular circuit is the onemeasured in tetrachloroethylene solution;

FIG. 8 shows the 60 mHz. nuclear magnetic resonance spectrum of thecopolymer employed in FIG. 7;

FIG. 9 shows the infrared spectrum of a solid film of an alternatingcopolymer of isoprene and ethylene of the present invention on rocksalt; and

FIG. 10 shows the 60 mHz. nuclear magnetic resonance spectrum of thecopolymer employed in FIG. 9.

The following results support the conclusion that the copolymer ofbutadiene and ethylene obtained by the present invention is analternating one.

1) In FIG. 1, it is found that microstructure of hutadiene units of thecopolymer is composed of trans-1,4, cis-1,4 and 1,2 configurations andmoreover it is rich in trans-1,4. The band ascribed to cis-l,4 butadieneunits, the one ascribed to ethylene units and the one ascribed to mainchain methylene group of 1,2-butadiene units may be overlapped at thebroad absorption which appeared at 722 cmr From the shape of the 722cm.- band, it is possible to confirm the existence of cis-1,4configuration, but it is impossible to measure it.

(2) In FIG. 2, the 4.60 peak is ascribed to overlapping of the twoprotons directly attached to the double bond of a 1,4-structurebutadiene unit and a methine pro ton of a pendant vinyl group of a 1,2butadiene unit. The 4951- peak is ascribed to methylene protons ofpendant vinyl group of a 1,2 butadiene unit. The ratio of 1,4 structureof a butadiene unit to that of a 1,2 structure was determined asfollows: if A is peak area of a 4.601- peak and B is peak area of a4.957- peak, the molar ratio of a 1,4 structure to 1,2 structure can beshown by the following equation;

1,4 structure A- %B 1,2 structure B Therefore, microstructure of thecopolymer shown in FIG. 2 is as follows:

Percent 1,4 structure 85.3 1,2 structure 14.7

ethylene -C'{%B+2(A%B)} It is found that the copolymer employed in FIG.2 is an equimolar copolymer of butadiene and ethylene.

(4) In FIG. 2, the spectrum measured in the region from about 7.51- to9.0T and shown shifted upward from the base line is the one measured bya mHz. spectrometer and the other one was measured by a 60 mHz.spectrometer. Intrinsic viscosity of the copolymer employed in FIG. 2was 2.38 (dL/g.) in toluene at 30 C. and its melting point was observedat 23 C. by DSC measurement. Therefore, on account of its highviscosity, in the 60 mHz. spectrum 8.577, 8.62-r and 8.72-1- peaks cannot be observed, but in the 100 mHz. spectrum these peaks can be seen.These peaks may mainly be ascribed to methylene groups of ethylene unitsof the copolymer and the shape of the peak (100 mHz.) is quite similarto the one in FIG. 8.

(5) The X-ray diagram of the copolymer employed in FIG. 1 and FIG. 2 isshown in FIG. 3. It was measured at 25 C. It is found that the copolymeris amorphous at 25 C. However, as can be seen in FIG. 4 on stretchingthe specimen at 25 C., two peaks appear at 20.4 and 23.0. The peakscorrespond to the ones appearing in the diagram of the copolymeremployed in FIG. 7 and FIG. 8.

(6) The copolymerization gives 1:1 copolymer over a wide range ofinitial monomer composition.

(7) The copolymerization reaction gives 1:1 copolymer independently ofpolymerization time.

(8) From the above results, it is concluded that the copolymer of thepresent invention is an alternating copolymer of butadiene and ethylenewhose microstructure of butadiene units is composed of trans-1,4,cis-1,4 and 1,2 structures.

The differences between the alternating copolymer of butadiene andethylene given in this invention and the one given by Natta previouslyare described below.

The copolymer of butadiene and ethylene prepared by the catalyst systemof triisobutylaluminum, vanadyl chloride and a partial hydrolysisreaction product of aluminum triisopropoxide (Japanese patent appln. No.21,996/ 1970) was employed as the sample of FIG. 7 and FIG. 8. FIGS. 7and 8 are given for reference purposes. Intrinsic viscosity measured intoluene at 30 C. was 0.39 (dL/g.) and its melting point was clearlyobserved at 73 C. by DSC measurement. In FIG. 7, cis-butadiene unit canscarcely be found in it and the butadiene unit of the copolymer is foundto be essentially trans-1,4. In FIG. 8, it is found that trans-1,4content of the copolymer is 94.0% and 1,2 content is 6.0%. In FIG. 7,the crystalliza tion sensitive bands at 1206, 1070 and 889 cm.- reportedby Natta are observed. The copolymer was shown to be highly crystallinein the X-ray diagram measured at room temperature and it showed twopeaks at angles 2=20.4 and 23.0. The copolymer is found to be anequimolar copolymer of butadiene and ethylene in FIG. 8.

From the above results, it was concluded that the copolymer employed inFIG. 7 and FIG. 8 is a highly crystalline alternating copolymer ofbutadiene and ethylene whose butadiene unit is essentially trans-1,4. Inother words, the copolymer is quite similar to the alternating copolymerof butadiene and ethylene reported by Natta previously.

When Bt is trans-1,4-butaidene unit, 30 is cis-l,4 butadiene unit, B is1,2 butadiene unit and E is ethylene unit, the structure of thealternating copolymer of this invention can be illustrated as below:

on the other hand, the ultimate structure of the alternat- Therefore,the alternating copolymer proposed by Natta is highly crystalline andhas a high melting point. The melting point of the copolymer employed inFIG. 7 and FIG. 8 was 73 C. and that of the ones reported by Natta was6065 C. As shown above, the microstructure of the butadiene unit of theultimate structure of the alternating copolymer proposed by Natta is alltrans-1,4 and therefore the ultimate melting point of the copolymershould be higher than 73 C.

On the other hand, the microstructure of the butadiene unit of thecopolymer of this invention is lacking in stereospecificity andtherefore crystallinity and melting point of the copolymer is lower thanthat of the one proposed by Natta. The copolymer of this invention showsrubberlike elasticity. However, the copolymer proposed by Natta does notshow rubber-like elasticity.

The alternating copolymer of butadiene and ethylene employed in FIG. 6shows its melting point at 32 C. In FIG. 7, the spectrum shown in therectangular circuit is the one measured in tetrachloroethylene.Therefore, 1464 cmr 1435 cm:- and 540 cm.- bands are also considered tohe crystallization sensitive bands of the crystalline alternatingcopolymer. In FIG.6, these crystallization sensitive bands also appearas a very weak band. n the other hand, from the band shape of the 722cm? band, the existence of cis-l,4 structure is apparent. The copolymeralso shows rubber-like elasticity. Therefore, it is found that thecrystallinity of the copolymer is higher than that of the one employedin FIG. 1 and FIG. 2, but the structure of the copolymer is similar tothe one employed in FIG. 1 and FIG. 2. In FIG. 1, only a trace of 1070cm. band can be seen as a weak and broad band at 1075 cmf Accordingly,it is concluded that the alternating copolymer of this inventioncorresponds to one obtained by randomly replacing optional amounts oftrans-l,4 butadiene units of the alternating copolymer of butadiene andethylene proposed by Natta with a cis-l,4 butadiene unit and (or) a 1,2butadiene unit.

By decreasing the stereospecificity of microstructure of the butadieneunit of the alternating copolymer of butadiene and ethylene proposed byNatta, the crystallinity and melting point of the copolymer decreasedand by further decreasing the stereospecificity of microstructure of thebutadiene unit of the copolymer, an alternating copolymer of butadieneand ethylene whose microstructure of the butadiene units is random canbe obtained. The copolymer shows no melting point, shows no X-raycrystallinity and is amorphous even on stretching or on cooling. It isnoteworthy that the distribution of butadiene unit and ethylene units ofthe copolymer is quite regular and only microstructure of the butadieneunits of the copolymer is random. And therefore, the copolymer is quitedifferent from an amorphous equimolar random copolymer of butadiene andethylene whose units of the two comonomers in the copolymer have randomdistribution.

It is concluded that the structure of the alternating copolymer ofbutadiene and ethylene of this invention is quite diiferent from that ofthe one proposed by Natta previously.

The alternating copolymer of butadiene and ethylene proposed by Miyoshishowed its melting point at 60 C.

and therefore, the copolymer is quite similar to the one proposed byNatta. The alternate copolymer of ethylene and butadiene of thisinvention shows a melting point of lower than 55 C. or shows no meltingpoint.

The following results support the conclusion that the copolymer ofisoprene and ethylene prepared by the method of the present invention isan alternating copolymer of isoprene and ethylene.

(1) In FIG. 9, it is found that microstructure of the isoprene units ofthe copolymer is substantially composed-of 1,4-structure and3,4-structure. There can be seen no peak near 909' cm." whichcorresponds to a band assigned to 1,2-structure of an isoprene unit. The890 crnr band and broad 840 cm.- band are assigned to 3,4- and1,4-structures of a isoprene unit of the copolymer, respectively.

(2) In FIG. 10, the triplet at 4.91 is ascribed to the proton directlyattached to a 1,4-isoprene double bond and the peak at 5.321 is ascribedto a isopropenyl methylene group of a 3,4-isoprene unit of thecopolymer. By measuring the ratio of peak area of the triplet at 4.91-to half of that of the peak at 5-327, the ratio of 1,4- structure to3,4-structure is found to be 63/37.

(3) Copolymer compositions were determined as follows: it A is peak areaof the triplet at 4.97, B is peak area of the peak at 5.321, and C ispeak area of the all peaks in the region from 7.5- to 9.57, the molarratio of isoprene to ethylene in the copolymer can be shown by thefollowing equation:

is oprene A &3 ethy1ene {C(7A+3B)}% It is found that the composition ofthe copolymer according to the NMR analysis substantially agrees wellwith the calculated value for the 1:1 copolymer of isoprene andethylene.

(4) The copolymerization reaction gives 1:1 copolymer over a wide rangeof initial monomer composition.

(5) The copolymerization reaction gives 1:1 copolymer independently ofpolymerization time.

(6) In FIG. 10, the 8.321- peask may be ascribed to a were held in a lowtemperature bath at --78 C. and varying amounts of an organoaluminumcompound solution in toluene (1 molar solution), 10.0 milliliters ofliquid butadiene and varying amounts of ethylene were put successivelyinto the vessels also employing the 5 methyl group of c1s-l,4-structureof an isoprene unit and usual, dry, air-free technlque. Thereafter, thevessels were the 8.42-r peak may be ascribed to the total of methylsealed and allowed to copolymerize at a predetermined graups oftrans-I,4- and 3,4-structures of isoprene units of temperature for 16hours. The results were summarized the copolymer. Therefore, it is foundthat cis-l,4 content 111 Table of the copolymer is higher than trans-1,4content. 10 Methyllsobutyl kelone Insoluble and Pentanfi Soluble As faras the inventors kngw, there is no prior art in fraction was collectedas an alternating copolymer of connection with an alternating copolymerof isoprene and butadlenfl and ethylene- The Infrared Spectra and NMRethylene nor of a process for its preparation. spectra of thesefractions listed in Table 1 were similar The alternating copolymer of aconjugated diene and to those in FIG. 1 and 'FIG. 2, respectively.Pentane inethylene whose microstructure of conjugated diene units sluble fr l n w thy e rl h r n om copolymer of is lacking instereospecificity given by the present invenethylene and butadiene andthe NMR spectra of these tion is concluded to be a novel material.fractions were simllar to the one 1n FIG. 5.

TABLE 1 (1) Catalysts Monomer, Organohquid aluminum butadiene compoundMmol 'IiX4 Mmol Carbonyl compound Mmol (mL) Experigient 0.50 T1011 0.05Isobutyric acid anhydride 0.125 10.0 0.50 T1011 0.05 Acetic acid 0.12510.0 0.50 T1011 0. 05 Acetone 0.125 10.0 1. 00 T1014 0. 10 Propionicacid anhydn 0. 10. 0 0.15 'IiOli 0.10 Benzophenone 0.05 10.0 0.50 'IiBri0.10 Isobutyl aldehyde".-- 0.10 10.0 0.50 'IiBn 0.10 Acetyl acetone 0.1010.0 1.00 'IiBn 0.10 Benzoyl peroxide... 0.25 10.0 0.50 TiBrc 0.10Isoamyl acetate 0.15 10.0 0.50 TiBn 0.10 Acetic acid anhydrlde 0.10 10.01 00 T1014 0.10 Diethylrnalonate 0.25 10.0

1 AllBu1=trlisobutylaluminum; AlEta=triethylalumlnum.

TABLE 1 2 Polymerization conditions Copolymer yield, grams Methylisobutyl ketone Pentane ininsoluble, soluble fracpentane solution(butadi- Temperable traction ene ethylene Monomer, ture Time(alternating random ethylene (g.) 0.) (hr.) copolymer) copolymer) 1:number: Expmmen e. 0 16 0. 1. 05 6. 0 -30 1e 0. 47 3. 17 6.0 -30 16 0.14 0. 92 7. 0 -30 1s 0. 68 1. 20 7.0 0 1s 0. 05 3.86 7.0 0 18 0.33 0.947.0 0 1a 0.11 3.55 7.0 -30 16 0.09 0.87 6.0 0 1e 0. 04 2.58 0.0 0 10 0.3.69 6.0 0 16 0.02 4. 29

The molar ratio of conjugated diene to ethylene in the EXAMPLE 2ethylene rich random copolymer of a conjugated diene and ethylene of thepresent invention is lower than (diene/ethylene In FIG. 5, there areobserved no butadiene-butadiene repeating units. It is found that thecopolymer is a crystalline polyethylene modified by 10 mol percentbutadiene units which are randomly distributed in the polymer mainchain.

The invention will be illustrated with reference to the followingexamples.

EXAMPLE 1 The usual, dry, air-free technique was employed and 5.0milliliters of toluene, varying amounts of titanium (W) halide solutionin toluene (1 molar solution) and varying amounts of carbonyl groupcontaining compound were put successively into 30 milliliter stainlesssteel reaction vessels at 25 C. Then, the vessels were left alone at 25C. for 10 minutes. Thereafter, the vessels The usual, dry, air-freetechnique was employed and 5 .0 milliliters of toluene, 0.10 milliliterof titanium (IV) chloride solution in toluene (1 molar solution) and0.05 g. of carbonyl group containing compound were put successively into30 milliliter stainless steel reaction vessels at 25 C. Then, thevessels were left alone at 25 C. for 10 minutes. Thereafter, the vesselswere held in a low temperature bath at 78 C. and varying amounts oftriisobutylaluminum solution in toluene (1 molar solution), 10.0milliliters liquid butadiene and 7.0 g. ethylene were put successivelyinto the vessels also employing the usual, dry, air-free technique.Thereafter, the vessels were sealed and allowed to copolymerize at 0 C.for 18 hours. The results were summarized in Table 2. The structure ofthe alternating copolymers and that of the random copolymers ofbutaciiene and ethylene were similar to the ones in Example 1,respectively.

TABLE 2 (1) Catalyst 1 Organo- Monomer, Experiment aluminum CarbonylLiquid number compound Mmol TiX; Mmol compound Gram butadliiiu;

1 AllBu: 1.00 TiCh 0.10 ('1'! 0.05 10.0

AHOQGH 2 AllBu; 1.00 TlCh 0.10 H 0.05 7.0

Zn(OCCH:)a

3. AliBul 0.50 TlCh 0. 10 l 0. 05 10.0

OV(OECH8)2 4 AliBu; 1.00 T1014 0.10 OTi(acac)a 0.05 10.0

1 AliBu;=triisobutylaluminum; AIEt triethylaIuminuni;0Ti(acae)z=titanium oxydiaeetylaeetonate.

TABLE 2 (2) Copoly'mer yield, grams Methyl iso- Polymerization butylketone Pentane inconditions insoluble, soluble fracpentane solution(butadi- Temperable fraction ene ethylene Monomer, me Time (alternatingrandom ethylene (g.) 0.) (hr.) copolymer) oopolymer) Experiment number:

EXAMPLE 3 TABLE 3 (2) i The usual, dry, air-free technique was employedand 5.0 milliliters of toluene and varying amounts of titanium Polymg ri zauon c 1 (IV) halide solution in toluene (1 molar solution) were congrams put into 30 milliliter stainless steel reaction vessels at ii/i um25 C. Then, the vessels were held in a low temperature 3,5 5,, Pentanebath at --78 C. and varying amounts of an organoaluinsoluble, insolublepentane fraction mmum compound solution in toluene (1 molar solution),Soluble (butadiene. varying amounts of liquid butadiene and varyingamounts fraction ethylene rl of ethylene were put successively into thevessels also 5:5 m? a ,5 53? employing the usual, dry, air-freetechnique. Thereafter, 16 0 D3 0 the vessels were sealed and allowed tocopoly'merize at 0 18 1 a predetermined temperature and for apredetermined 18 -3 0 18 Trace 1. 18 time. The results were summarizedin Table 3. In the m 2o Trace 2. 6 -20 19 0.10 3.04

infrared spectra of the alternating copolymers in Table 3, as shown inFIG. 6, a weak and sharp 1070 cm:- band appeared, respectively.

x AlBu;=triisobutylalumiuum; AlEta=triethylaluminum.

EXAMPLE 4 The usual, dry, air-free technique was employed and varyingamounts of toluene, varying amounts of carbonyl compound and varyingamounts of titanium (IV) chloride solution in toluene (1 molar solution)were put successively into 30 milliliter stainless steel reactionvessels at 25 C. Then, the vessels were held in a constant temperaturebath maintained at a predetermined temperature (it corresponds tocatalyst preparation temperature in Table 4 listed below) and varyingamounts of triisobutylaluminum solution in toluene (1 molar solution) 14The structure of the copolymer was similar to the one shown inExample 1. Chloroform insoluble fraction was ethylene rich randomcopolymer of butadiene and ethylene. Butadiene content of the copolymerwas 6.2 mol percent. The yield of the copolymer was 4.39 g.

EXAMPLE 6 The usual, dry, air-free technique was employed and 5.0milliliters of toluene, 0.10 milliliter of titanium (IV) halide solutionin toluene (1 molar solution) and 0.25

TABLE 4 (1) Monomers Catalysts Catalyst preparation Solvent, LiquidAliBus, TiCli, tern eratoluene butadiene Ethylene Mmol Mmol Carbonylcompound Mmol ture( C.) (ml.) (ml.) (g.) Experiment number:

TiCKOPJCaHg);

2.50 0.05 Propionic acid anhydride--.. 0.10 78 5.0 10.0 2.0 0.30 10.10Acetophenone 0.10 78 15.0 2.0 8.0

TABLE 4 (2) Polymerization conditions Copolymer Methyl ethyl ketoneinsoluble, chloroform soluble fraction (alternating copolymer)chloroform in- Butadiene soluble fraction microstructure (butadieneethylene ran- 1,2 1,4 domcopolymer Temperature Time Yield (g.)

( 0.) (hr.) (g.) Percent Experiment number:

0 18 0.58 9 91 0.20 40 18 0.01 85 0.38 40 18 0.06 13 87 Trace 0 18 0.1415 85 0.10 40 18 0. 15 13 87 4. 75

EXAMPLE 5 millimole of carbonyl group containing compound were Theusual, dry, air-free technique was employed and 10.0 milliliters oftoluene, 0.10 millimole of benzo phenone, 0.10 milliliter of titanium(IV) chloride solution in toluene (1 molar solution) and 0.30 milliliterof triisobutylaluminum solution in toluene (1 molar solution) were putsuccessively into a 30 milliliter stainless steel reaction vessel at C.Then, the vessel was held in a low temperature bath at 78 C. and 10.0milliliters of liquid butadiene and 8.0 g. of ethylene were put into thevessel also employing the usual, dry, air-free technique. Thereafter,the vessel'was sealed and allowed to copolymerize at 20 C. for 5 hours.Yield of the methyl ethyl ketone insoluble and chloroform solublefraction, i.e. alternating copolymer of butadiene-"and ethylene was 1.49g. Its intrinsic viscosity was 1.2 (dL/g.) in chloroform at C. Themicrostructure of butadiene unit of the copolymer was as follows:

put successively into 30 milliliter stainless steel reaction vessels at25 C. Then, the vessels were left alone at 25 C. for 10 hours.Thereafter, the vessels were held in a low temperature bath at 78 C. and1.00 milliliter of triisobutylaluminum solution in toluene (1 molarsolution), 5.0 milliliters of liquid isoprene and 8.0 g. of ethylenewere put into the vessels also employing the usual, dry, air-freetechnique. Thereafter, the vessels were sealed and allowed tocopolymerize at 0 C. for 24 hours. The results were summarized in Table5. Methyl ethyl 'ketone insoluble and chloroform soluble fraction wasgathered as an alternating copolymer of isoprene and ethylene. Theinfrared spectra and NMR spectra of the alternating copolymers in Table.5 were similar to those in FIG. 9 and FIG. 10, respectively. Thechloroform in- Prcent soluble fractions were found to be randomcopolyr'ners 1,2 12 of isoprene and ethylene whose isoprene contentswere 1,4 88 1-3 mol percent from their NMR spectra.

TABLE 5 (1) Catalysts Monomers Organo- Liquid aluminum isoprene Ethylenecompound Mmol T1X Mmol Carbonyl compound Mmol (ml.) (g.) Experiment 1.00 TiCl 0.10 Propioni acid anhydride 0.25 5.0 8.0 1.00 TiCh 0.10 Aceticacid 0.25 5.0 8.0 1.00 TiCh 0.10 Isobutyl aldehyde 0.25 5.0 8.0 1.00TiCh 0.10 Isoamyl acetate 0.25 5.0 8.0 1.00 TiBr; 0.10 Isobutyric acidanhydride 0.25 5.0 8.0 1.00 TiBn 0.10 Benzophenono 0.25 5.0 8.0

TABLE 5(2) Copolyiner Methyl ethyl ketone insoluble, chloroform solublefraction (alternating copolymer) Isoprene Chloroform in- Polymerizationmicrostructure Soluble fraction conditions (isoprene- 1, 4 3, 4 ethyleneTempera- Time Yield random ture C.) (g.) Percent copolymer) (g.)Experiment number- EXAMPLE 7 ethyl ketone and soluble in chloroform was2.40 g. The

aluminum compound solution in toluene (1 molar solution), 50 millilitersof liquid isoprene and 8.0 g. of ethylene were put successively into thevessels also employing the usual, dry, air-free technique. Thereafter,the vessels were sealed and allowed to copolymerize at a predeterminedtemperature and for a predetermined time. The results were summarized inTable 6.

microstructure of isoprene units of the alternating copolymer was asfollows:

Percent EXAMPLE 9 The usual, dry, air-free technique was employed and10.0 milliliters of toluene, 0.20 millimole of benzophen- TABLE 6 (1)Polymerization Catalyst Monomers conditions Organo- Liquid Temp aluminumTiCli, lsoprene Ethylene erature Time compound Mmol Minol (ml. (g.) 0.)(hr.)

Experiment number:

0.25 0.10 5.0 3.0 is 1.00 0.10 so 8.0 o 24 0.25 am 5.0 8.0 0 17 TABLE 6(2) one, 0.20 milliliter of titanium (IV) chloride solution in c 1 intoluene (1 molar solution), 1.00 milliliter of triisobutylyme'ye gramsaluminum solution in toluene (1 molar solution), 10.0 Methyl ethylmilliliters of liquid isoprene and 4.0 g. of ethylene were ketoneChloroform insoluble insoluble put successively into a 30 millilitersstainless steel reaction ch lg rg f gm gc vessel at 7 8 C. Then, thebottle was sealed and allowed {motion ethglene to copolymerize at 0 C.for 5 hours. The yield of altergz gs a hating copolymer of isoprene andethylene insoluble in p m m methyl ethyl ketone and soluble inchloroform was 1.39 g. Er i i eggi gnt The microstructure of isopreneunits of the alternating Q04 M2 copolymer was as follows:

318i 313i Percent 1,4 59 50 3,4- 41 EXAMPLE 8 We claim:

The usual, dry, air-free technique was employed and 10.0 milliliters oftoluene, 0.10 millimole 1. A process for preparing a polymerizationproduct selected from the group consisting of a 1:1 alternatingcopolymer of a conjugated diene and ethylene having rubbet-likeeleasticity', the microstructure of the conjugated diene of whichcopolymer is lacking in stereospecificity, and a mixture of saidalternating copolymer and an ethylene rich random copolymer of ethyleneand said conjugated diene, comprising contacting ethylene and theconjugated diene in liquid phase with a catalyst consisting essentiallyof an organoaluminum compound having the formula AlR wherein Rrepresents a C -C hydrocarbon radical selected from the group consistingof alkyl, cycloalkyl, aryl and aralkyl radicals and a titaniumtetrahalide,

17 wherein the molar ratio of the organoaluminum compound to thetitanium tetrahalide is from 1.5 to 50.

2. A process as claimed in claim 1 wherein a carbonyl group containingcompound is further included as a component of the catalyst.

3. A process as claimed in claim 2 wherein the molar ratio of thecarbonyl group containing compound to the titanium tetrahalide is withina range from 0.01 to 20.

4. A process as claimed in claim 1 wherein the conjugated diene has from4 to 12 carbon atoms in the molecule.

5. A process as claimed in claim 4 wherein the conjugated diene has from4 to 5 carbon atoms in the molecule.

6. A process as claimed in claim 1 wherein the organoaluminum compoundis triethylaluminum or triisobutylaluminum.

7. A process as claimed in claim 1 wherein the catalyst is prepared at atemperature within a range from -100 C. to +100 C.

8. A process as claimed in claim 1 wherein the copolymerization iscarried out at a temperature within a range from 100 C. to +100 C.

9. A process as claimed in claim 1 wherein the copolymerization isconducted in the form of solution polymerization by using an inertorganic solvent.

10. A process as claimed in claim 9 wherein the solvent is selected fromthe group consisting of an aromatic hydrocarbon, an aliphatichydrocarbon and a halogenated hydrocarbon.

11. A process as claimed in claim 1, wherein said conjugated diene hasfrom 4 to 5 carbon atoms in the molecule, R is a C -C alkyl radical,both of the temperatures for catalyst preparation and forcopolymerization are within a range from 78 C. to +50 C., and thecoplymerization is carried out in the form of solution polymerization byusing a diluent selected from the group consisting of an aromatichydrocarbon, an aliphatic hydrocarbon and a halogenated hydrocarbon.

12. A process as claimed in claim 11 wherein a carbonyl group containingcompound is further included as a component of the catalyst in an amountto give a molar ratio of the carbonyl group containing compound to thetitanium tetrahalide within a range from 0.02 to 10.

13. The process of claim 1, wherein the polymerization product is said1:1 alternating copolymer.

14. The process of claim 1, wherein the polymerization product is saidmixture of said alternating copolymer and said random copolymer.

15. A 1:1 alternating copolymer of ethylene and a conjugated dienehaving rubber-like elasticity, the microstructure of the conjugateddiene units of which copolymer is lacking in sterospecificity.

16. An alternating copolymer as claimed in claim 15 wherein saidconjugated diene has from 4 to 12 carbon atoms in the molecule.

17. An alternating copolymer as claimed in claim 15 wherein saidconjugated diene is butadiene or isoprene.

18. An alternating copolymer as claimed in claim 17 wherein theconjugated diene is butadiene and the melting point of the copolymer islower than C.

19. An alternating copolymer as claimed in claim 17 wherein theconjugated diene is butadiene and said copolymer shows no melting point.

References Cited UNITED STATES PATENTS 2,968,650 1/ 1961 Baxter et al.260-85.3 3,163,611 12/1964 Anderson et al 252-429 3,590,024 6/1971Ishizuka et al. 260-853 R 3,657,208 4/1972 Judy 26093.1

OTHER REFERENCES Reich and Schindler: Polymerization by OrganometallicCompounds, Interscience, New York (1968), pp. 686-8.

JOSEPH L. SCHOF-ER, Primary Examiner A. I-IOLLER, Assistant Examiner

